Soil Structure: Five Basic Layers

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

How does the soil live and why is it degrading. Part 1

“If you have two coins, buy soil for one of them, and greens for the other. And soon you will have your dream home and food. And if you are tired, work a little in the garden, and the tiredness will pass,”say the old proverbs.

In our soddy-podzolic soils, the reserves of nutrients are very scarce, growing plants often starve due to lack of food, it is difficult to grow a good harvest, and it is almost impossible to obtain the ecological quality of vegetable products. A way out can be found if you learn how to properly enrich the soil, achieving a positive balance of nutrients in a particular summer cottage.

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In this article, we will talk about how the soil lives, whether it is enriched with plant nutrients or degrades, losing fertility residues, we will consider the cycle and balance of nutrients in the natural environment of the summer cottage, as well as the measures necessary to ensure that the soil does not dying and bringing joy to the gardener.

Many have heard of "soil", but not everyone knows what soil is. Agrarian science calls soil the uppermost layer of the earth with a thickness of about 1-2-3 meters. More than one hundred and thousand years passed until, as a result of the soil-forming process, the soil was formed from the parent rock under the influence of plants, animals, microorganisms, sunlight, temperature and precipitation. The soil is hidden from our view, and only its uppermost horizon is revealed to us, it is called the arable horizon.

According to the genetic structure, all soils consist of several layers, differing from each other in their physicochemical structure.

Arable layer

Soil cut

Sod-podzolic soils of the North-West zone consist of approximately five layers, the profile of such a soil can be seen if you make a soil section (see Fig.). The top layer is arable, most valuable, more fertile and richer in nutrients. In it, in the process of dying off of plants and microorganisms, organic substances are concentrated, which stimulate the further process of soil formation.

Only plants can collect nutrients from all layers of the soil with their roots, accumulate them in themselves, and after dying off, enrich this upper layer of the earth with nutrients. In the original soils, it is small 5-8 cm (this is a forest litter), and for agricultural plants a more powerful layer is needed - up to 20-28 cm. And only a person, the owner of a summer cottage, can increase its capacity if he correctly cultivates the soil and her organic and mineral fertilizers in the right quantities.

Podzolic layer

The second layer of soil is called podzolic (A), it is completely sterile, has a whitish color like the color of ash, is formed from the parent rock as a result of washing with acidic plant secretions and excess atmospheric precipitation, it has an acidic environment unfavorable for plants, therefore, it is dangerous for root growth …

When using agricultural soil, a person must get rid of this layer, which is unfavorable for plants. However, simple physical plowing is not enough for this. It is impossible to get rid of it instantly, simply by digging up the soil, in one step or one year. In this case, the entire arable layer (forest litter) will die, it will be diluted and acidified, the plants simply cannot grow on such a mixture. The thickness of the podzolic layer is different in different soils, from 3 to 7-15 cm. Therefore, it will take 3-8 years to develop this layer.

It is allowed to plow no more than 1-2 cm per year to the arable horizon, and then on condition that 10 kg / m ^{2 of} good manure, 50 g / m ^{2 of} superphosphate and 200 g / m ^{2 of} dolomite flour are applied to each centimeter of the layer to be plowed. Only with such measures in a few years the arable horizon will increase to 25-28 cm, and the podzolic horizon will disappear, and the soil can be considered reclaimed.

Illuvial layer

The third soil horizon is called illuvial (B _{1 is} transitional and B _{2 is} an inflow horizon), it is more dense. Compaction occurs as a result of washing in various substances from the upper layers of the soil, it contains many colloidal (clay) particles, iron and aluminum sesquioxides, by the way, very toxic for plants, its thickness is 50-150 cm. The increased density of this horizon, the presence ferrous compounds inhibit the growth and respiration of the roots. It can be improved only by deep loosening with special tools or by complex manual digging in layers, or digging locally at the bottom of the planting pit during planting of fruit crops.

Mother breed

Next comes the parent rock (C), from which all the upper layers of the soil were formed. The composition and fertility of the entire soil depends on the chemical composition of the parent rock. The soil cannot contain more plant nutrients than the parent rock. In the history of the Earth, the territory of the North-West region was once covered by the waters of the ocean, the water then receded and took away all the soluble nutrients.

Therefore, our soils by their origin are initially very poor in all nutrients and, especially, nitrogen, phosphorus, iodine, copper, cobalt, molybdenum, boron and some other microelements are in short supply for plants. Therefore, animals and humans may experience endemic diseases associated with a deficiency of these elements in the soil and in plants - food. Therefore, our soils (due to poverty) belong to the zone of risky farming, where it is simply impossible to grow a full harvest and high-quality food without the introduction of organic and mineral fertilizers.

For cognitive purposes, the upper arable horizon of sod-podzolic soil can be divided into five component parts (phases): one part is mineral substances (sandy particles 0.05-1 mm, clayey - 0.001-0.05 mm, colloidal - less than 0.001 mm), they account for an average of 270 kg / m ² of the total mass per square meter with a depth of 25 cm, the second part is organic matter (plant residues, dead microorganisms and humic substances), 13-20 kg / m ² of the total soil mass, the third part is soil air, it weighs almost nothing, the fourth part is a soil solution, it accounts for 10-20 kg / m ², a fifth is the living phase of the soil (microorganisms, fungi, algae, worms, insects, mammals, etc. other organisms) to 20 kg / m ²… All soil phases are necessary and important for growing plants.

It is especially valuable that the relationships between the phases of the soil are not disturbed and preserved. This is the special concern of the gardener. If the relationships between the phases of the soil and the integrity of the genetic layers of the soil are violated by the gardener, then it degrades, the soil in this case dies. Soil degradation occurs in different ways, that is, for various reasons, and the intensity of this process depends only on the activities of the gardener and vegetable grower.

The functioning of soils is the result of the action of a complex complex of natural, biochemical and biophysical mechanisms, including that of humans. The soil is a universal environment, where biogeochemical processes are cyclical, conditions for plant life are created, the hydrological regime of the entire ecosystem and the composition of the atmosphere are regulated. The soil in this case serves as a protective and favorable screen for all living things, a converter and accumulator of organic matter in the arable layer of the soil.

Vasily R. Williams

Vasily R. Williams, a well-known soil scientist, in his writings clearly showed how and from what soil appears. He wrote: “The entire chemistry of the soil is no more than a function of its organic matter, and, moreover, a substance, partly dead, partly revived by the most active intense life, and in the parent rock, in the products of weathering of rocks, we do not meet that active, incessantly going chemism just because this breed is dead.

Bring organic matter into it - you bring life into it, and very quickly the dead parent rock will turn into a living complex, linking the mineral rock with organic, dead with living, - it will turn into soil. Therefore, organic fertilizers play a leading role in soil life and plant nutrition. Without the use of organic fertilizers, the breed and soil remain dead and unsuitable for growing quality food for humans.

Depending on the use of the soil in the country, it is necessary to distinguish several ecological zones in which soil processes - domestication or degradation - proceed in different ways. The plot must be divided into a residential area, a vegetable garden, a garden, a flower garden-lawn and a protected ground area. It is recommended to delimit all these zones with grooves for storm water drainage, they can also be used in the dry season as paths.

The soil surface in each zone must be flat so that surface water can be easily removed, not retained, in order to prevent the development of stagnant bog processes in depressions. Each square meter of arable soil layer 25 cm deep is expensive, on average at least 400 rubles. Therefore, the upper arable soil horizon from the territory of the future residential zone is simply removed and used to level and improve the soil in other areas.

Read the next part. Cycle of nutrients and soil texture →

Gennady Vasyaev, Associate Professor, Ch. specialist of the North-West Regional Scientific Center of the Russian Agricultural Academy

Olga Vasyaeva, amateur gardener

Read all parts of the article How the soil lives and why it degrades

Part 1. The structure of the soil: five basic layers

Part 2. The cycle of nutrients and the mechanical composition of the soil

Part 3. Soil degradation